Abstract The framework of pediatric inactivity triad (PIT) consists of three core factors:exercise deficit disorder, pediatric dynapenia, and physical illiteracy. It emphasizes that physical activity (PA) insufficiency is not a singular phenomenon but rather a vicious cycle resulting from the interaction of multiple factors. Based on the PIT framework, the paper explores its core components and their interrelationships, as well as analyzes the framework s application value and practical implications for improving PA levels among Chinese children and adolescents,to provide a systematic theoretical perspective for analyzing the complex causes of PA insufficiency in children and adolescents, and to offer a scientific basis for developing intervention strategies.